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From: bgaensler@cfa.harvard.edu
Subject: epchain needed for accurate timing?
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4 replies: 1 2 3 4
4 followups: 1 2 3 4

Private message: yes  no

Notes:

Notification:


Date: Tue, 2 Mar 2004 14:47:27 GMT
From: bgaensler@cfa.harvard.edu
To: xmmhelp@xmm.vilspa.esa.es
CC: bgaensler@cfa.harvard.edu
Subject: epchain needed for accurate timing?
Full_Name: Bryan Gaensler
Submission from: (NULL) (131.142.41.105)


Dear Helpdesk,

I am carrying out a period search on an XMM observation taken in
EPIC pn small window mode. I want to know whether I need
to reprocess my data before doing this search.

In XMM Newsletter #22 (15 Apr 2002), it was stated:

"In the earlier SAS releases the true period of a periodic source could be only
determined  to one part in 10**-6 due to a coding error in the task "barycen".
For the Crab pulsar the new results now conform with estimates of the 
theoretically attainable accuracy with XMM-Newton and the expected 
statistical errors. Further investigations for periods of other objects are
currently underway.

Because of another improvement in converting the onboard time to the
event time, the user should make sure that the data are reprocessed
completely with the new SAS 5.3 and not only with the new "barycen"
task."

For more recent data, does one still need to reprocess the data completely with
epchain before carrying out a timing analysis, or are the event lists
supplied in the PPS directory suitable for analysis, once one has
run the "barycen" task? My observation was performed in March 2003.

thanks,

Bryan



Reply 1

Resend
From: Pedro M. Rodriguez Pascual <xmmhelp@xmm.vilspa.esa.es>
To: bgaensler@cfa.harvard.edu
Subject: Re: epchain needed for accurate timing? (PR#10306)
Date: Tue Mar  2 15:38:08 2004
Dear Bryan, 

Since the release of the XMM Newsletter #22 other concerns about timing have
been found (see the attached document and helpdesk questions related to
"barycen").

In two days a new version of SAS (6.0) will be released where events
time-tagging is significantly better handled. Therefore, we would recommend you
reprocess (i.e., from epchain) your data with this new release SAS6.0, though
the actual effect on the scientific results strongly depends on the nature and
quality of the data.

Sincerely, 

Pedro


> Full_Name: Bryan Gaensler
> Submission from: (NULL) (131.142.41.105)
> 
> 
> Dear Helpdesk,
> 
> I am carrying out a period search on an XMM observation taken in
> EPIC pn small window mode. I want to know whether I need
> to reprocess my data before doing this search.
> 
> In XMM Newsletter #22 (15 Apr 2002), it was stated:
> 
> "In the earlier SAS releases the true period of a periodic source could be
only
> determined  to one part in 10**-6 due to a coding error in the task
"barycen".
> For the Crab pulsar the new results now conform with estimates of the 
> theoretically attainable accuracy with XMM-Newton and the expected 
> statistical errors. Further investigations for periods of other objects
are
> currently underway.
> 
> Because of another improvement in converting the onboard time to the
> event time, the user should make sure that the data are reprocessed
> completely with the new SAS 5.3 and not only with the new "barycen"
> task."
> 
> For more recent data, does one still need to reprocess the data completely
with
> epchain before carrying out a timing analysis, or are the event lists
> supplied in the PPS directory suitable for analysis, once one has
> run the "barycen" task? My observation was performed in March 2003.
> 
> thanks,
> 
> Bryan
> 
> 
> 


Followup 1

Compose reply
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Date: Tue, 2 Mar 2004 10:38:36 -0500
From: Bryan Gaensler <bgaensler@cfa.harvard.edu>
To: "Pedro M. Rodriguez Pascual" <xmmhelp@xmm.vilspa.esa.es>
Cc: Bryan Gaensler <bgaensler@cfa.harvard.edu>
Subject: Re: epchain needed for accurate timing? (PR#10306)
Hi Pedro,

> Since the release of the XMM Newsletter #22 other concerns about timing
have
> been found (see the attached document and helpdesk questions related to
> "barycen").

I didn't get the attached document - can you resend?
 
> In two days a new version of SAS (6.0) will be released where events
> time-tagging is significantly better handled. Therefore, we would recommend
you
> reprocess (i.e., from epchain) your data with this new release SAS6.0,
though

Great! But will SAS 6.0 be compatible with RedHat Linux v9.0? I currently
can't run epchain with SAS v5.4 because of incompatibility problems.

regards
Bryan



Reply 2

Resend
From: Pedro M. Rodriguez Pascual <xmmhelp@xmm.vilspa.esa.es>
To: bgaensler@cfa.harvard.edu
Subject: Re: epchain needed for accurate timing? (PR#10306)
Date: Tue Mar  2 15:42:47 2004
> Hi Pedro,
> 
>> Since the release of the XMM Newsletter #22 other concerns about timing
have
>> been found (see the attached document and helpdesk questions related
to
>> "barycen").
> 
> I didn't get the attached document - can you resend?
>  

I was just sending it from my personal account.

>> In two days a new version of SAS (6.0) will be released where events
>> time-tagging is significantly better handled. Therefore, we would
recommend
> you
>> reprocess (i.e., from epchain) your data with this new release SAS6.0,
though
> 
> Great! But will SAS 6.0 be compatible with RedHat Linux v9.0? I currently
> can't run epchain with SAS v5.4 because of incompatibility problems.
> 

It is.

Regards, 

Pedro


Followup 2

Compose reply
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Date: Tue, 2 Mar 2004 10:44:05 -0500
From: Bryan Gaensler <bgaensler@cfa.harvard.edu>
To: "Pedro M. Rodriguez Pascual" <xmmhelp@xmm.vilspa.esa.es>
Cc: Bryan Gaensler <bgaensler@cfa.harvard.edu>
Subject: Re: epchain needed for accurate timing? (PR#10306)
Hi Pedro,

> > I didn't get the attached document - can you resend?
> I was just sending it from my personal account.

I think your message bounced, because it exceeded the maximum message
size of 8 MB allowed for our mail system. Can you transmit in compressed
form, or make this information available via ftp or WWW?

regards
Bryan



Followup 3

Compose reply
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Date: Tue, 2 Mar 2004 11:01:41 -0500
From: Bryan Gaensler <bgaensler@cfa.harvard.edu>
To: "Pedro M. Rodriguez Pascual" <xmmhelp@xmm.vilspa.esa.es>
Cc: Bryan Gaensler <bgaensler@cfa.harvard.edu>
Subject: Re: epchain needed for accurate timing? (PR#10306)
> Since the release of the XMM Newsletter #22 other concerns about timing
have
> been found (see the attached document and helpdesk questions related to
> "barycen").

Hi Pedro,

Were there also some helpdesk questions you were going to forward,
or just the document which you sent?

regards
Bryan



Reply 3

Resend
From: Pedro M. Rodriguez Pascual <xmmhelp@xmm.vilspa.esa.es>
To: bgaensler@cfa.harvard.edu
Subject: Re: epchain needed for accurate timing? (PR#10306)
Date: Tue Mar  2 16:14:25 2004
Hi Bryan, 

there are several questions that can be found after searching for "barcyen" with
the helpdesk search facility

Pedro

> > Since the release of the XMM Newsletter #22 other concerns about
timing
have
>> been found (see the attached document and helpdesk questions related
to
>> "barycen").
> 
> Hi Pedro,
> 
> Were there also some helpdesk questions you were going to forward,
> or just the document which you sent?
> 
> regards
> Bryan
> 
> 


Followup 4

Compose reply
Download message
Date: Tue, 2 Mar 2004 11:14:44 -0500
From: Bryan Gaensler <bgaensler@cfa.harvard.edu>
To: "Pedro M. Rodriguez Pascual" <xmmhelp@xmm.vilspa.esa.es>
Subject: Re: epchain needed for accurate timing? (PR#10306)
>there are several questions that can be found after searching for "barcyen"
with
>the helpdesk search facility

Hi Pedro,

I did this and read all the corresponding discussions, but none seemed
to focus on possible problems with SAS v5.3 barycen.  Can you point me
towards particular threads which might be relevant?

regards
Bryan



Reply 4

Resend
From: Pedro M. Rodriguez Pascual <xmmhelp@xmm.vilspa.esa.es>
To: bgaensler@cfa.harvard.edu
Subject: Re: epchain needed for accurate timing? (PR#10306)
Date: Tue Mar  2 16:30:11 2004
Dear Bryan, 


they are not referred directly/explicitely to SAS5.3 but to general timing
problems identified after release SAS5.3 and, therefore, not properly treated in
it.

Sincerely, 

Pedro


> >there are several questions that can be found after searching for
"barcyen"
> with
>>the helpdesk search facility
> 
> Hi Pedro,
> 
> I did this and read all the corresponding discussions, but none seemed
> to focus on possible problems with SAS v5.3 barycen.  Can you point me
> towards particular threads which might be relevant?
> 
> regards
> Bryan
> 
> 

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